is it possible to switch an other channel as 10 to a drumchannel? I like to use an other drumset additive. Otherwise I have to create an additional instance of the soundsource. I've tryed it by SysEx-Command , but it doesen't work

Yes, drum tracks in MusE can use any channel.
The Arranger Track List has a 'Channel' column.
Simply double-click the entry and an adjustment box will pop up.
(Also, mouse right-click and middle-click will adjust the value.)
By default it is set to channel 10 for drum tracks.